Peel daikon, cucumber and turnip, and slice 1/4" thick. Layer whole cabbage leaves, sliced daikon, cucumber and turnip in a large bowl. Between layers, liberally sprinkle with 1/2 cup salt. Cover with water and place a wide plate or pot on top to submerge them. Leave overnight or at least 12 hours. Drain & Rinse vegetables in a colander. Julienne each vegetable into a uniform shape. return them to the large bowl, and add spring onions, garlic, ginger, chili flakes, soy/tamari, salt and 1 cup water. Toss to combine. Spoon the vegetables with liquid into a large crock or clean jars. Cover tightly or cap. Refrigerate for 3 days before opening. Everyday, turn jars upside down a couple of times to distribute spices, or stir vegetables in the crock. Store in refrigerator.